The process of simplification of Japanese kanji characters in Grennia began in the late 1990s, as the government at the time in collaboration with Grennia's Japanese community sought to create a new simplified form of Japanese writing with the goal of creating a distinct Japanese-Grennian identity, through means of using and standardising ryakuji common in Grennia, borrowing from Simplified Chinese, and aiming to take better example of both semantic and phonological roots.

The first phase of simplification came into effect on July 19, 2000 after a referendum supporting the simplification was approved by Grennian voters, who voted 76.2% in favour of simplification. However even before then, the first simplification standards were being extensively discussed beginning in March of 1998 with the formation of the Revised Script Committee, a government branch tasked with standardising and promoting simplification.

Below are the kanji characters and radicals simplified in Phase One, in handwritten form.

After the adoption of the first phase of simplification, the Revised Script Committee began work on a second simplification phase beginning in February of 2007. Throughout the 2000s, many Grennians had quickly began to embrace simplified kanji characters as a way of showing a unique linguistic pride for Grennia, which at the time had only been an independent nation for no longer than around half a decade. With this in mind, a second phase of simplification was quickly approved and came into effect on September 3, 2009.

Below are the kanji characters and radicals simplified in Phase Two, in handwritten form.